Adaptive polling of wireless devices

ABSTRACT

In a wireless network, the decision of when and whether to send unsolicited polls to a particular mobile wireless device may be made by monitoring communications conditions affecting the ability of the particular device to gain channel access, and sending unsolicited polls if the ability to gain channel access is below a threshold value. Such conditions may include one or more of channel load, device transmission load, collision rate, and number of mobile wireless devices contending for access.

BACKGROUND

In a wireless local area network (WLAN), there are generally two networkmechanisms that allow wireless devices to get channel access:distributed and centrally-coordinated. In the distributed mechanism,each mobile wireless device (STA) may try to transmit when it thinks thechannel is going to be free, but sometimes multiple STAs transmit at thesame time and thereby interfere with each other, causing a need forretries. In the centrally-coordinated mechanism, a coordinating device,such as an access point (AP), may poll each STA in turn, giving thepolled STA exclusive use of the channel for a while. This may preventcollisions and retries by allowing only one STA to transmit at a time,but some STAs may experience communication delays because they have towait while the AP is polling other STAs that have nothing to transmit.

Rather than waiting for its turn to be polled, a STA with data totransmit may send a short request to the central coordinator that theSTA be polled for one or more longer-duration transmissions.Alternately, the central coordinator may send out unsolicited polls toone or more STAs. Which of the methods (contention for the channel,unsolicited polls, or solicitations to be polled) provides the bestoverall channel throughput may depend on various things such as channelconditions, which may change dynamically with time. Conventionalnetworks may send out unsolicited polls on a fixed schedule, a techniquethat responsive to changing channel conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by referring to the followingdescription and accompanying drawings that are used to illustrateembodiments of the invention. In the drawings:

FIG. 1 shows a flow chart of a method of determining whether to sendunsolicited polls, according to an embodiment of the invention.

FIG. 2 shows a flow chart of a method of determining whether to sendunsolicited polls, according to another embodiment of the invention.

FIG. 3 shows a diagram of a wireless network in which unsolicited pollsmay be issued, according to an embodiment of the invention.

FIG. 4 shows a wireless device, according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth.However, it is understood that embodiments of the invention may bepracticed without these specific details. In other instances, well-knowncircuits, structures and techniques have not been shown in detail inorder not to obscure an understanding of this description.

References to “one embodiment”, “an embodiment”, “example embodiment”,“various embodiments”, etc., indicate that the embodiment(s) of theinvention so described may include a particular feature, structure, orcharacteristic, but not every embodiment necessarily includes theparticular feature, structure, or characteristic. Further, repeated useof the phrase “in an embodiment” does not necessarily refer to the sameembodiment, although it may.

In the following description and claims, the terms “coupled” and“connected,” along with their derivatives, may be used. It should beunderstood that these terms are not intended as synonyms for each other.Rather, in particular embodiments, “connected” may be used to indicatethat two or more elements are in direct physical or electrical contactwith each other. “Coupled” may mean that two or more elements are indirect physical or electrical contact. However, “coupled” may also meanthat two or more elements are not in direct contact with each other, butyet still co-operate or interact with each other.

In the context of this document, the term “wireless” and its derivativesmay be used to describe circuits, devices, systems, methods, techniques,communications channels, etc., that may communicate data through the useof modulated electromagnetic radiation at least partially through anon-solid medium. The term does not imply that the associated devices donot contain any wires, although in some embodiments they might not.

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specificationdiscussions utilizing terms such as “processing,” “computing,”“calculating,” “determining,” or the like, refer to the action and/orprocesses of a computer or computing system, or similar electroniccomputing device, that manipulate and/or transform data represented asphysical, such as electronic, quantities within the computing system'sregisters and/or memories into other data similarly represented asphysical quantities within the computing system's memories, registers orother such information storage, transmission or display devices.

In a similar manner, the term “processor” may refer to any device orportion of a device that processes electronic data from registers and/ormemory to transform that electronic data into other electronic data thatmay be stored in registers and/or memory. A “computing platform” maycomprise one or more processors.

As used herein, unless otherwise specified the use of the ordinaladjectives “first”, “second”, “third”, etc., to describe a commonobject, merely indicate that different instances of like objects arebeing referred to, and are not intended to imply that the objects sodescribed must be in a given sequence, either temporally, spatially, inranking, or in any other manner.

Embodiments of the invention may be implemented in one or a combinationof hardware, firmware, and software. Embodiments of the invention mayalso be implemented as instructions stored on a machine-readable medium,which may be read and executed by a computing platform to perform theoperations described herein. A machine-readable medium may include anymechanism for storing or transmitting information in a form readable bya machine (e.g., a computer). For example, a machine-readable medium mayinclude read only memory (ROM); random access memory (RAM); magneticdisk storage media; optical storage media; flash memory devices;electrical, optical, acoustical or other form of propagated signals(e.g., carrier waves, infrared signals, digital signals, the interfacesthat transmit and/or receive those signals, etc.), and others.

In keeping with common industry terminology, the terms “base station”,“access point”, and “AP” may be used interchangeably herein to describean electronic device that may communicate wirelessly with multiple otherelectronic devices, while the terms “mobile wireless device” and “STA”may be used interchangeably to describe any of those multiple otherelectronic devices, which may have the capability to be moved and stillcommunicate with the AP, though movement is not a requirement. However,the scope of the invention is not limited to devices that are labeledwith these terms.

Various embodiments of the invention may generate unsolicited polls toSTAs at least partly on the basis of some indication of the observedcommunications load. Such observed communications load may include oneor more of such things as channel load, device transmission load,collision rate, and/or contention for channel access. Such observationsmay be based on actual transmissions and/or on indicator(s) of the dataqueued up for transmission.

FIG. 1 shows a flow chart of a method of determining whether to sendunsolicited polls, according to an embodiment of the invention. Flowchart 100 begins at 110 with a monitoring period, during which one ormore indicators of channel availability may be monitored. Channelavailability may indicate how easily a given device (such as a mobilewireless device) is likely to be able to acquire access to the channelfor transmission. The monitoring period may be scheduled in variousways, such as but not limited to: 1) at regular intervals, 2) atirregular intervals based on detection of some triggering event orcondition, 3) a continuously rolling period, 4) in other ways notspecifically listed here. As indicated at 120, the monitoring mayinclude monitoring channel load (e.g., the fraction of time the channelis busy as measured over a period of time). The precise definition of‘channel’ may vary depending on the type of transmission technologybeing used, such as but not limited to frequency division multipleaccess (FDMA), code division multiple access (CDMA), spatial divisionmultiple access (SDMA), orthogonal frequency division multiplexing(OFDM), and any combination of multiple techniques, but in general twodevices transmitting at the same time whose signals interfere with oneanother sufficiently to impair usable reception may be considered to beon the same channel.

When a channel is busy may be determined in various ways, such asdirectly by detecting a carrier signal on the channel, indirectly bygetting an indication of the amount of data in the transmit queues ofdevices that use the channel and calculating what percentage of time thechannel is estimated to be busy based on the data in these queues, or bya combination of these and/or other techniques. Transmit queues maycomprise data that is temporarily stored while awaiting transmission,and/or the location at which that data is temporarily stored. Transmitqueues may be implemented through software, memory locations, hardwarebuffers, and/or any other feasible means. A given device may have one ormore transmit queues, and the use of the plural term “queues” herein isalso intended to cover instances in which only one queue is used.

At 130, the transmission load of a particular mobile wireless device maybe monitored to determine how much access the particular mobile wirelessdevice needs to the channel. The device transmission load may bedetermined in various ways, such as directly by monitoring thetransmissions from that device, indirectly by examining the transmitqueue(s) of that device and calculating how much access to the channelthat the device may need, or by a combination of these and/or othertechniques. In the illustrated embodiment of FIG. 1 the channel load anddevice transmission load may be monitored concurrently so that theresultant determinations will be for approximately the same time period,but other embodiments may use other techniques, such as but not limitedto monitoring channel load and device transmission load at separatetimes.

Such monitoring may continue until the monitoring time period isdetermined to be over at 140. As implied above, the monitoring periodfor channel load and the monitoring period for device transmission loadmay be separate and may not begin or end at the same time. After themonitoring period is over, the values for the specific load parametersmay be determined at 150. Such load parameters may include any or allof, but are not limited to, a parameter for channel load, a parameterfor device transmission load, and a composite parameter combiningchannel load and device transmission load in a predetermined manner. Oneor more of the parameters may be compared against one or more thresholdvalues at 160 to device whether conditions justify sending unsolicitedpolls to the particular mobile wireless device mentioned above.

Depending on the results of the comparison(s) at 160, one or moreunsolicited polls may be sent to the particular mobile wireless deviceat 170, or such polls may not be sent to the particular mobile wirelessdevice at 180. In some embodiments, the unsolicited polls may be sent ifboth of the following two conditions are true, while in other embodimentthe unsolicited polls may be sent if either of these conditions istrue: 1) the channel load parameter is greater than the associatedchannel load threshold value, indicating that the channel is so busythat the particular mobile wireless device may have trouble gainingaccess to the channel as often as it needs, and 2) the devicetransmission load parameter for the particular mobile wireless device isgreater than the associated device transmission load threshold value,indicating the particular mobile wireless device has so much data tosend that it may not me able to send the data in a timely manner unlessit is given dedicated channel access by being polled. If either or bothof the conditions is not true (depending on the embodiment), unsolicitedpolls may not be sent at that time, based on a determination that theparticular mobile wireless device does not need channel accesssufficiently to justify giving it immediate exclusive access by means ofan unsolicited poll. While specific conditions have been listed hereinas criteria for the decision, it is understood that in some embodiments,other conditions not listed here may override the decisions described.

In other embodiments, the channel load and device transmission load maybe merged into a single combined parameter, and that combined parametercompared with a threshold value to determine whether or not to sendunsolicited polls. The combined parameter may be created from theindividual parameters through various techniques, such as but notlimited to: 1) adding the individual parameters, 2) adding weighedvalues of the individual parameters, 3) multiplying the individualparameters, 4) multiplying weighted values of the individual parameters,5) a combination of these or other techniques, 6), etc.

Although the comparison operations described herein may refer to amonitored value being ‘greater than’ or ‘less than’ the threshold value,it is understood that other mathematical techniques may be used thatwould reverse the ‘greater than’/‘less than’ relationship, or that wouldinclude ‘equal to’ on either side of the decision point. Suchdifferences amount to minor variations that would be obvious to a personof ordinary skill in the art and are considered to be within the scopeof the various embodiments of the invention.

FIG. 2 shows a flow chart of a method of determining whether to sendunsolicited polls, according to another embodiment of the invention.Flow chart 200 is similar to flow chart 100, except that channelcollision rate is monitored at 220 instead of channel load, and thenumber of contending mobile wireless devices is monitored at 230 insteadof device transmission load. Except for the substitution of these twoparameters, the description of FIG. 2 is similar to the description ofFIG. 1, with designators 2 xx substituting for designators 1 xx, and thedescription is therefore not repeated here. Although FIG. 1 shows twoparticular criteria being used in the decision of whether to sendunsolicited polls, and FIG. 2 shows two other criteria, it should benoted that in some embodiments any of the four indicated criteria may beused either singly or in any combination to determine whether to sendunsolicited polls.

A collision occurs when two or more devices attempt to transmit at thesame time and the resulting combination of their signals prevents atleast one of them from being accurately received by the intendedreceiver. Such collisions may usually be inferred when a transmission isstrong enough to be received correctly but is corrupted such that itcannot be reconstructed at the receiving device. Since such collisionswill presumably not occur if the two devices are transmitting ondifferent channels, the channel collision rate may only be concernedwith collisions on the particular channel being used. If the collisionrate is high, that may indicate that too many devices are contending forchannel access and that the contention should be reduced or eliminatedby polling devices individually to give them exclusive use of thechannel for a limited time. In some embodiments a single device, such asbut not limited to a base station, may determine the collision rate bymonitoring all transmissions on the channel and determining how many ofthose transmissions have been corrupted. In other embodiments, multipledevices may monitor for collisions and the collision statistics may beperiodically collected from those devices and combined to produce achannel collision rate. In still other embodiments, each device maymonitor only its own collision rate, and may report that collision rateto a central collection point, such as the AP, if that collision rateexceeds a certain level.

The number of mobile wireless devices contending for access to thechannel, as indicated at 230, may be determined in various ways. In someembodiments, the AP may keep track of the number of mobile wirelessdevices that transmit data on the channel and/or request the AP to grantthem access to the channel during the monitoring period. It may also beinferred by using the amount of data in the transmit queues of themobile wireless devices to estimate how many devices are anticipated tocontend for channel access during a particular period of time. Theamount of data in a mobile wireless device's transmit queues may learnedby the AP in various ways, such as but not limited to: 1) the mobilewireless device may include an indication of the amount of dataremaining in its queues in a message to the AP, 2) the AP may estimatethe amount of data based on the content of messages being sent to themobile wireless device, 3) etc.

FIG. 3 shows a diagram of a wireless network in which unsolicited pollsmay be issued, according to an embodiment of the invention. In theillustrated network 300, an AP 310 may communicate with multiple mobilewireless devices 331, 332, 333 and 334. Each device is shown with anantenna (320 for the AP and 341-344 for the STAs) through which thedevice may transmit and receive signals according to the protocols ofthe communications technology being used. The AP may receive and/orotherwise monitor signals transmitted by each of the STAs and maytransmit to each of the STAs, while each of the STAs may receive and/ormonitor signals from the AP. In some embodiments at least one STA maymonitor or otherwise communication directly with another STA, althoughthe invention is not limited in this respect. Although only one antennais shown per device, some or all of the devices may have more than oneantenna. Each antenna may be of various types, such as but not limitedto a dipole antenna and/or an omni-directional antenna.

FIG. 4 shows a wireless device, according to an embodiment of theinvention. Although the wireless device and its antenna are labeled 331and 341, corresponding with an exemplary STA in FIG. 3, the drawing mayalso illustrate the components of an AP. In the illustrated embodimentof FIG. 4, computing platform 450 may be coupled to antenna 341 throughmodulator/demodulator 420, analog to digital converter (ADC) 430, anddigital to analog converter (DAC) 440. The ADC and DAC may convertsignals between analog and digital formats, while themodulator/demodulator may convert between the analog signals and a highfrequency signal suitable for wireless communications. Other componentsnot shown may also be included.

The foregoing description is intended to be illustrative and notlimiting. Variations will occur to those of skill in the art. Thosevariations are intended to be included in the various embodiments of theinvention, which are limited only by the spirit and scope of theappended claims.

1. A method, comprising: monitoring channel availability for a mobilewireless device; comparing the channel availability with a value; andtransmitting an unsolicited poll to the mobile wireless device resultantto the channel availability being less than the value.
 2. The method ofclaim 1, wherein said monitoring comprises monitoring transmittedsignals on the channel.
 3. The method of claim 1, wherein saidmonitoring comprises determining an indication of an amount of data inat least one transmit queue of the mobile wireless device.
 4. The methodof claim 1, wherein said channel availability is indicated by at leastone of channel load, device transmission load, channel collision rate,and contention for channel access.
 5. The method of claim 1, whereinsaid channel availability is indicated by a combination of channel loadand device transmission load.
 6. The method of claim 1, wherein saidchannel availability is indicated by at least one of a channel collisionrate indicator and a contention for channel access indicator.
 7. Anarticle comprising a machine-readable medium that provides instructions,which when executed by a computing platform, cause said computingplatform to perform operations comprising: monitoring channelavailability for a mobile wireless device; comparing the channelavailability with a value; and transmitting an unsolicited poll to themobile wireless device resultant to the channel availability being lessthan the value.
 8. The article of claim 7, wherein said monitoringcomprises monitoring transmitted signals on the channel.
 9. The articleof claim 7, wherein said monitoring comprises monitoring transmitqueues.
 10. The article of claim 7, wherein said channel availability isindicated by at least one of channel load, device transmission load,channel collision rate, and contention for channel access.
 11. Thearticle of claim 7, wherein said channel availability is indicated by acombination of channel load and device transmission load.
 12. Thearticle of claim 7, wherein said channel availability is indicated by atleast one of a channel collision rate indicator and a contention forchannel access indicator.
 13. An apparatus comprising a wireless deviceto: monitor at least one indicator of channel availability for aparticular mobile wireless device; determine at least one parameterbased on said monitoring; compare said at least one parameter with atleast one threshold value; and transmit an unsolicited poll to theparticular mobile wireless device resultant to the comparison indicatingthat channel availability is less than a predetermined level of channelavailability.
 14. The apparatus of claim 13, wherein the at least oneindicator includes at least one indicator selected from a listconsisting of: a channel load indicator; a device transmission loadindicator; a channel collision rate indicator; and a device contentionindicator.
 15. The apparatus of claim 13, wherein said monitoringcomprises monitoring transmitted signals on the channel.
 16. Theapparatus of claim 13, wherein said monitoring comprises monitoring atleast one transmit queue.
 17. The apparatus of claim 13, wherein said dwireless device is a base station.
 18. The apparatus of claim 13,wherein said wireless device is a device selected from a list consistingof: the particular mobile wireless device; and a mobile wireless deviceother than the particular mobile wireless device.
 19. A systemcomprising a wireless device comprising an omni-directional antenna, thewireless device to: monitor at least one indicator of channelavailability for a particular mobile wireless device; determine at leastone parameter based on said monitoring; compare said at least oneparameter with at least one threshold value; and transmit an unsolicitedpoll to the particular mobile wireless device resultant to thecomparison indicating that channel availability is less than apredetermined level of channel availability.
 20. The system of claim 19,wherein the at least one indicator includes at least one indicatorselected from a list consisting of: a channel load indicator; a devicetransmission load indicator; a channel collision rate indicator; and adevice contention indicator.
 21. The system of claim 19, wherein saidmonitoring comprises monitoring transmitted signals on the channel. 22.The system of claim 19, wherein said monitoring comprises monitoring atleast one transmit queue.
 23. The system of claim 19, wherein saidwireless device is a base station.
 24. The system of claim 19, whereinsaid wireless device is a device selected from a list consisting of: theparticular mobile wireless device; and a mobile wireless device otherthan the particular mobile wireless device.